1. Field of the Invention
The present invention is generally related to an actuation system and, more particularly, to a gear selector actuation device that is used to select forward, reverse, and neutral gear positions in conjunction with the marine propulsion system.
2. Description of the Prior Art
Push-pull cables are well known to those skilled in the art and used in many different applications to allow an operator to actuate a movement at a location which is spaced apart from the location of the operator. These types of devices are used to actuate brakes and gear selectors on motorcycles, snowmobiles, bicycles, and marine vessels. When used in conjunction with marine vessels, the push-pull cable can be used to actuate gear selector mechanisms and throttle position selectors.
U.S. Pat. No. 3,613,632, which issued to Farrell on Oct. 19, 1971, describes a combined steering, shift and throttle control for outboard, inboard, or inboard-outboard powered boats. The invention provides a single capstan lever which is pivoted upon the front of the boat for tilting movement to right or left and is connected through push-pull cables or similar devices to a steerable outboard rudder or to the outboard part of the inboard-outboard drive combination at the rear of the boat to effect steering control of the boat and the shift and throttle of the outboard motor part or rudder. This capstan lever has handles extending from the top thereof which can be grasped by the pilot to effect steering movement of the lever. The upper end of the capstan lever is flared and tightly receives the removable casings of throttle and shift levers that are connected through push-pull cables with the outboard or inboard motor. Various connections are made from the capstan lever to the outboard motor to effect the steering of the outboard motor, not only in the form of a push-pull cable, but rod linkage and telemetric hydraulic cylindrical device. An instrument panel may be provided upon the capstan where it can be easily viewed by the pilot.
U.S. Pat. No. 4,952,181, which issued to Entringer et al on Aug. 28, 1990, discloses a marine shift cable assembly with a spring guide. A shift cable assembly for a marine drive having a clutch and gear assembly includes a remote control for selectively positioning the clutch and gear assembly into forward, neutral, and reverse gear, a control cable connecting the remote control to a shift lever pivotally mounted on a shift plate, a drive cable connecting the shift lever on the shift plate to the clutch and gear assembly, and a spring guide assembly with compression rings biased to a loaded condition by movement of the remote control from neutral to forward and also biased to a load condition by movement of the remote control from neutral to reverse. The bias minimized chatter of the clutch and gear assembly upon shifting into gear, and aids shifting out of gear and minimized slow shifting out of gear and returns the remote control to neutral, all with minimum backlash of the cables. The spring guide assembly includes an outer tube mounted to the shift plate, and a spring biased plunger axially reciprocal in the outer tube and mounted at its outer end to the shift lever.
U.S. Pat. No. 5,207,116, which issued to Sultze on May 4, 1993, describes a cable core length adjuster mechanism. The mechanism provides adjustment for a push-pull cable system having a core disposed within a conduit. The core and the conduit are flexible for much of their length, with the core being a rigid rod at the ends. An end of one of the rods is slidably disposed within a body of the adjuster mechanism. The body has a generally rectangular shape, elongated in an axial direction. The body has a means of swivelable attachment integrated into it. The body has a rectangular opening through it which is perpendicular to the axis from a top to a bottom. There are teeth transverse to the axis in the opening on the sides paralleling the axis. A clip is disposed in the opening. The clip can be manually moved from an adjust position to an engaged position. It has teeth complementary to the teeth in the opening that engage those teeth when the clip is in an engaged position by pressing it into the body. When the clip is in the adjust position, the teeth are not engaged. In the adjust position, the clip is snapped over the rod end, axially engaging it in a circumferential groove of the rod end. A spring disposed between the body and the clip biases the body relative to the clip.
U.S. Pat. No. 6,077,136, which issued to Arai et al on Jun. 20, 2000, describes an outboard motor control. A shift and throttle control mechanism allows for control of the shift and throttle features of an outboard motor through two separate operators. For instance, one operator can be remotely positioned in the hull in an associated watercraft, while the other operator can be formed on a steering handle of the outboard motor. The shift and throttle control mechanism is also configured to fit within a cowling of the outboard motor, together with a four cycle engine, without significantly increasing the size of the cowling. In one mode, the shift and throttle control mechanism includes a shift shaft arranged toward the front side of the engine. One of the operators is directly connected to the shift shaft by a linkage rod. The other operator is connected by a shift control cable to a shift lever that is located on the side on the engine. This location of the lever allows the end of the shift control cable to be fixed within the cowling without increasing the cowling""s size. A link connects the shift lever to the shift shaft, which in turn actuates a shift rod to control a transmission of the outboard motor.
U.S. Pat. No. 4,794,820, which issued to Floeter on Jan. 3, 1989, discloses a marine drive twin lever remote control with interlock override. A twin lever control actuator operates push-pull cables and has two sets of pulleys on opposite sides of a control body. Interlock structure normally prevents movement of the shift lever and its cable when the throttle lever and its cable are in a high speed position and with the operator applying normal force to the shift lever. Override structure permits movement of the shift lever and its cable with the throttle lever in a high speed position when the operator applies an abnormally high force to the shift lever to enable emergency high speed shifting including from forward to reverse, to facilitate rapid deceleration.
U.S. Pat. No. 4,753,618, which issued to Entringer on Jun. 28, 1988, discloses a shift cable assembly for a marine drive. The device includes a shift plate, a shift lever pivotally mounted on the plate, and a switch actuating arm pivotally mounted on the plate between a first neutral and a second switch actuating position. A control cable and drive cable interconnect the shift lever and switching actuating arm with a remote control and clutch and gear assembly for the marine drive so that shifting of the remote control by a boat operator moves the cables to pivot the shift lever and switch actuating arm which in turn actuates a shift interrupter switch mounted on the plate to momentarily interrupt ignition of the drive unit to permit easily shifting into forward, neutral, and reverse gears. A spring biases the arm into its neutral position and the arm includes an improved mounting for retaining the spring in its proper location on the arm.
U.S. Pat. No. 4,231,316, which issued to Bland et al on Nov. 4, 1980, describes an actuation means for a marine propulsion device transmission. The device includes a shiftable, reversing transmission located in a propulsion unit and connecting a driveshaft to a propeller shaft and a shifting mechanism including an actuation member connected to the transmission. Movement of the actuating member to shift the transmission between a neutral condition and forward drive and reverse drive conditions is effected by a shifting system including a flexible dual cable conduit assembly connected between the actuating member and a shift lever mounted for reciprocal movement. The opposite ends of the two shift cables are linked together in a manner such that the movement of the shift lever in opposite directions causes alternate pulling of the shift cables to shift the transmission.
The patents described above are hereby expressly incorporated by reference in the description of the present invention.
In an actuation system that incorporates a push-pull cable, an inherent problem exists with regard to the movement of the internal wire within the external sheath, or casing, of the cable. Because of the requirement that clearance be provided between the outer surface of the wire and the inner surface of the casing, or sheath, the wire can bend within the internal cavity of the sheath. This can result in the loss of motion between the movement of the wire at a control end of the cable and the resulting movement of the wire at an actuation end of the cable. The principle elements of lost motion in a control system are backlash and deflection. Backlash is caused by the core member, or wire, moving inside the casing, or sheath, with the change in direction of motion. It is a function of the clearance between the core and casing and the total number of degrees of bend in the cable. The other loss of motion is deflection of the core wire under compressive load. Elastic strain in the core member due to compressive or tensile force also contributes to the loss of motion. Although this loss of motion can be reduced by careful design, they represent an inherent potential problem in applications where the precise degree of travel at the control end of the wire, or core, is important. These problems are significantly exacerbated as a function of the length of the push-pull cable, with longer cables exhibiting more significant loss of motion at the actuator end.
It would therefore be significantly beneficial if an actuation system could be provided in which an adjustment can be made at the actuation end of a push-pull cable system to select the range of travel of a device that is actuated by the actuation end of a push-pull cable.
An actuation system, made in accordance with the preferred embodiment of the present invention, comprises a push-pull cable having a control end and an actuation end, with the push-pull cable comprising a sheath with a wire disposed within the sheath. Throughout the description of the present invention, it should be understood that the sheath is a tubular casing and the wire is disposed within the internal cavity of the tubular casing. The present invention further comprises an actuator attached to the wire at the actuation end. A rotatable component is supported for rotation about a first axis and a link arm is connected between the rotatable component and the actuator. The link arm is attached to the rotatable component at a point which is spaced apart from the first axis. A motion directing component is associated with the actuator to determine the path of travel of the actuator in response to movement of the wire at the actuation end of the push-pull cable. The position of the motion directing component is adjustable relative to the rotatable component.
A preferred embodiment of the present invention further comprises an anchor member attached to the actuation end of the sheath. The anchor member is rotatable about a second axis. The motion directing component comprises a channel portion, in a particular preferred embodiment, and the actuator is disposed within the channel portion. The channel portion limits movement of the actuator to a restricted path in response to movement of the wire relative to the sheath at the actuation end of the push-pull cable. In a preferred embodiment, the restricted path is generally a straight line, but it should be understood that other shapes can be selected to achieve certain desired results. For example, a generally S-shaped or sinusoidal path could be provided so that the effect on the movement of the rotatable component is more symmetrical as a result of movement of the actuator in opposite directions from a central position.
A position retention mechanism, such as a screw, bolt, or pin, is provided to prevent movement of the motion directing component relative to the rotatable component except when the position of the motion directing component is being manually adjusted. The position retention mechanism comprises a protrusion on the position retention mechanism and a recess formed in a surface to which the position retention mechanism is attached. The recess is shaped to receive the protrusion and, in combination with the bolt, holds the motion directing component in a fixed position during operation.
The rotatable component is attached to a shift shaft of a marine propulsion system in a particularly preferred embodiment. Rotation of the rotatable component causes synchronous rotation of the shift shaft to result in a change of gear position between the forward, neutral, and reverse gear positions.
A manually controlled gear position selector is provided and connected to the control end of the push-pull cable, whereby movement of the manually controlled gear position selector causes the wire to move within the sheath.